Coumarin contents of tonka (Dipteryx odorata) products

Tonka (Dipteryx odorata) is a plant native in tropical Africa. The tonka fruits contain a kernel, commercialized as tonka beans. These kernels are known to contain coumarin, a natural flavoring compound widely used in foods and pastries, beverages, and cosmetics. Coumarin is known to be liver toxic and therefore authorities have regulated its contents in foods and alcoholic beverages. The purpose of this study was to quantify the concentration of coumarin in different foods and beverages that contain tonka beans or were prepared thereof. The tonka beans itself or the products thereof were extracted with methanol and these extracts were analyzed using a HPLC-UV/Vis method. We have extracted and measured 20.4 ± 0.4 to 43.4 ± 0.9 mg coumarin per gram in six samples of tonka beans. In sugars aromatized with tonka (n = 3) 0.2 ± 0.0 mg/g of coumarin were observed and in two pastes produced from tonka 0.6 ± 0.0 mg/g were determined. A handcrafted ‘Tonka Gin’ was containing 2.2 ± 0.0 mg/L. Based on the non-observed-adverse-effect level (NOAEL) for hepatotoxicity in animal experiments, the Scientific Panel on Food Additives Flavorings, Processing Aids and Materials in Contact with Food (AFC) established a Tolerable Daily Intake (TDI) of 0.1 mg/kg bw (body weight) coumarin. We suggest to critically evaluate whether the TDI could be exceeded by consuming the products tested containing coumarin.